Abstract: It is disclosed a method for operating an improved internal combustion engine. An intake valve and an exhaust valve control closing and opening of respective intake and exhaust apertures. The engine includes a separating aperture between the cylinder and a separation chamber, and a controlling separating valve. The separation chamber is connected to the intake and exhaust manifolds respectively by the intake and exhaust apertures. The method includes opening the separating valve. While it is open, the exhaust valve opens and then closes, and then the intake valve opens enabling gas flow from the intake manifold to the cylinder volume through the open intake aperture, the separation chamber and the open separating aperture. The method includes closing the intake valve and closing the separating valve. Thereby, gas flow from the intake manifold stops, isolating the separation chamber from the cylinder volume and providing double isolation during compression and combustion strokes.

Abstract: It is provided an improved internal combustion engine unit. The engine unit has a piston moving in a cylinder enclosing cylinder volume, an intake valve controlling closing and opening of an intake aperture connecting the cylinder volume to an intake manifold, and an exhaust valve controlling closing and opening of an exhaust aperture connecting the cylinder volume to an exhaust manifold. The improved engine unit includes a separating aperture between the cylinder and a separation chamber, and a separating valve adapted for controlling closing and opening the separating aperture. The separation chamber is connectable to the intake manifold and to the exhaust manifold, respectively, by the intake and exhaust apertures. Opening both the separating valve and the exhaust valve enables gas flow from the cylinder volume to the exhaust manifold through the open separating aperture, the separation chamber and the open exhaust aperture.

Abstract: It is provided an improved internal combustion engine unit. The engine unit has a piston moving in a cylinder enclosing cylinder volume, an intake valve controlling closing and opening of an intake aperture connecting the cylinder volume to an intake manifold, and an exhaust valve controlling closing and opening of an exhaust aperture connecting the cylinder volume to an exhaust manifold. The improved engine unit includes a separating aperture between the cylinder and a separation chamber, and a separating valve adapted for controlling closing and opening the separating aperture. The separation chamber is connectable to the intake manifold and to the exhaust manifold, respectively, by the intake and exhaust apertures. Opening both the separating valve and the exhaust valve enables gas flow from the cylinder volume to the exhaust manifold through the open separating aperture, the separation chamber and the open exhaust aperture.